Medical endoscopes are inserted into the patient either through an orifice, incision, or other entry point. In many applications, the critical dimension of the orifice is smaller than the diameter of the endoscope cross-section, which means the orifice expands to accommodate the endoscope. Depending on the tissue structure, mechanical properties, and proximity to nerves, the deformation caused by insertion of the endoscope may result in tissue trauma and pain.
To reduce pain, many times the diameter of the endoscope is reduced; however, the diameter must be large enough to contain the functional components of the endoscope, and as such the diameter is often practically limited.